Originally Posted by WhatRoughBeast
All the statistics sites list "deaths reported that day." "Reported" means reaching the final stage of the information being received and listed by the relevant state agency and then getting passed on to whomever's posting the graphs. The weekly patterns relate mostly to which hospital departments and public health departments and intermediate state agencies are closed on weekend days, meaning not many of them reach the final tally point on Sun. or Mon.
In their internal reports, Massachusetts back-dates each death to the date it actually occurred, and also back-dates each new case (new positive test result) to the date the swab was taken. That makes the time series a lot smoother (though there's still a lull in new cases each Sun-Mon because fewer tests are actually performed on those days). But the Massachusetts data you see at Google or Worldometer doesn't show the back-dating. They want one number per measure per day (new deaths reported, new cases reported) and don't want to have to change the numbers from previous days. So you're seeing the crude sloppy data, and you can't easily discern trends on time scales shorter than weekly.